3" vs. Dual 3" vs. 5" as supply lines

I am on a department where the only supply hose we lay is 5", on everything. We have plenty of hydrants and the water system comes from the "big city" right next to us so amount and pressure is not really an issue. Some of us are talking about the idea of going to 3" or dual 3's for residentual fire runs. Some of the reasoning behind this is the gpm's you can get from 3" would be significant to supply attack lines on residentual fires and maneuverability of the hose on the ground. I would like to hear from everyone especially from those that lay 3" or dual 3's. What is your reasoning for it and what are the pro's and con's.

I am on a department where the only supply hose we lay is 5", on everything. We have plenty of hydrants and the water system comes from the "big city" right next to us so amount and pressure is not really an issue. Some of us are talking about the idea of going to 3" or dual 3's for residentual fire runs. Some of the reasoning behind this is the gpm's you can get from 3" would be significant to supply attack lines on residentual fires and maneuverability of the hose on the ground. I would like to hear from everyone especially from those that lay 3" or dual 3's. What is your reasoning for it and what are the pro's and con's.

So you lay 5 inch hose now? So instead of laying in one 5 inch line and getting all the available water and picking up one line, you want to lay one 3 inch and restrict available water or lay two 3 inch lines and get probably enough water and then have twice as much hose to pick up.

I must agree with fyredup here. Why play games? You have the hose to give you max available water, just lay the 5 inch and you know you're set. Why bother laying 3 inch and hope it doesn't turn into a prolonged operation where you are supplying multiple lines, deck guns, ladder pipes, etc? Why mess around laying 2 seperate 3inch supply lines for no reason, when you have what you need. Doesn't make alot of sense.

I personally like the keep it simple stupid method. One application to fit all needs. Just because some people are smarter than others to figure out how much water flow will I need on the structure fire before they get there, others might not be able to doit as quickly. Lay the 5" and take the guessing game out of it. Just my thoughts.

Why change if you already have the 5"? Guess you department has money to burn if you want to make that switch. Ask your taxpayers if they want to buy more hose just because you want to switch. I'm one for fiscal responsibility and treating a taxpayers money with respect. Switching for the sake of switching does not make sense. Years ago my department got rid of all of its 2 1/2" because the 1 3/4" was supposed to save the world, cure cancer and eliminate male pattern baldness. Guess what? We are now carrying 2 1/2" and it cost the department an arm and a leg to re-outfit 22 engine companies and my hair line is still receding.

Like any change, you need to analyze the ups and downs. If you currently use 5" hose, my guess is people are intimidated by it and dont want to pick up hose after fires. One thing you can do to fix that (if its the issue) is learn there are easy ways to pack it.

I'll give you some data, then some opinion.

Here is a side by side comparison of supply hose capability using a friction loss card provided by Snap Tite/Ponn. All hose will have slight to substantial variations in friction loss based on brand and age etc. The point here is to show a relative comparison.

The below numbers assume a maximum working pressure of 300 PSI for 3" and 200 PSI for 5". 15 PSI is subtracted for safety on maximum pressures and 20 PSI is assumed as the residual pressure.

Single 3" will move
500 GPM approximately 1300 Feet
750 GPM approximately 600 Feet
1000 GPM less than 300 Feet
The above numbers assume the line is being pumped at the hydrant at 285 PSI

If you have a hydrant that has 20 PSI residual at 500 GPM, then you are only going to get that flow at about 100 feet from the hydrant using a single 3" lay

To see what kind of performance to expect from your 3" hose, flow the above flows with your engine (using a pitot gauge or flow meter) and record the residual pressure on the intake guage of the pump for each flow. Look at a friction loss chart to see what the friction loss is for each flow and you'll get an idea how far you can move that flow without an engine on the hydrant.

If your second due engine is a way out, you cannot expect substantial performance of the 3" (especially single lay) until it is boosted.

Dual 3" will move
500 GPM approximately 5700 Feet
750 GPM approximately 2400 Feet
1000 GPM approximately 1300 Feet
The above numbers assume the line is being pumped at the hydrant at 285 PSI

Single 4" is essentially equivalent to dual 3"

Single Supply Grade 5" will move
500 GPM approximately 9700 feet
750 GPM approximately 4400 feet
1000 GPM approximately 2500 feet
1500 GPM approximately 1100 feet
2000 GPM approximately 625 feet
The above numbers assume the line is being pumped at the hydrant at 185 PSI

The reason 5" is ideal is because prior to the second due engine boosting the pressure, it allows more water to flow. For example, at 1000 GPM with a 40 PSI residual hydrant you'll get the water about 300 feet. Thats nothing compared to 2500 when its boosted by the next engine.

Remember, my numbers are very ballpark and meant to show the comparative differences.

My crude formula is...

MP-15-20/FL=__Hundred feet

Where MP is hose max pressure, 15 PSI for safety, 20 PSI for residual and FL is friction loss for chosen flow.

The answer will be in the number of hundred of feet for the chosen flow from the chart. I usually round down since our hose doesnt come in odd lengths.

If high pressures used above freak out your people, insert your maximum happy discharge number in the MP slot. Obviously if you pump at lower pressures you lose distance and flow.

A few of my thoughts...
We carry double jacket attack grade 4" now capable of 300 PSI (read 285 if used with a safety cushion) on the rig i am assigned to. Our engines carry supply grade 5" in split beds. We drop line for any reported structural fire.

The new engine we are awaiting delivery of will carry 1000' of attack grade 4" and 5 or 600 feet od 3". We don;t currently have 3" and will use it for supply to augment the 4", for FDC's, for vehicle fires when a supply is needed such as truck fires etc.

Places like DC or PG that run dual 3" lines have a second or 3rd due engine hot on their tails, equating to a quick supply being established. If you have to wait for a few minutes, stick with the 5".

Another example, FDNY runs 3.5" supply line. They are usually on the hydrant as the attack engine and are quite capable of moving the necessary amount of water since they have a 5 or 6" soft sleeve connection. You'll typically see their 3.5" line being used to feed tower ladders.

Hopefully guys from these places will chime in to this topic.

Questions to ask...

What are your real hydrant flows (flow and pressure) Get the graphs from the water co.

How far apart are your hydrants?

How much 5" do you carry?

How much 3" do you want to carry?

What will you take off, if anything to make room for 3"?

Do you need to purchase hosebed dividers for split 3" beds?

What will it cost?

Where did you get this idea?

What are your initial attack line flows?

How far out is your next due engine?

How big are your booster tanks on initial attack apparatus?

If you go to 3" hose, do you have the necessary gate valves and in line booster valves if required to make the switchover?

If you lay 3" line and charge a hydrant, how will the next engine be able to use the steamer port if a larger line is needed w/o shutting down the operation?

I am on a department where the only supply hose we lay is 5", on everything. We have plenty of hydrants and the water system comes from the "big city" right next to us so amount and pressure is not really an issue. Some of us are talking about the idea of going to 3" or dual 3's for residentual fire runs. Some of the reasoning behind this is the gpm's you can get from 3" would be significant to supply attack lines on residentual fires and maneuverability of the hose on the ground. I would like to hear from everyone especially from those that lay 3" or dual 3's. What is your reasoning for it and what are the pro's and con's.

Why would you want to go backwards?

It's like going from driving a Mustang GT to a Model T!

My FD went to 4" supply line in 2002 after years of dropping dual 3's.
Better water flow, less line to pick up and you don't have to wash and hang it!

‎"The education of a firefighter and the continued education of a firefighter is what makes "real" firefighters. Continuous skill development is the core of progressive firefighting. We learn by doing and doing it again and again, both on the training ground and the fireground."
Lt. Ray McCormack, FDNY

If you currently have 5 in hose you probably have plenty of water on residentual fires. Why would anyone want to decrease their water supply?

The only real advantage I can see between the 5 in and the dual 3 in is that in a dual 3 in lay you have two independent supply lines. If one line bursts you have a reduced flow, but you still will have water as you replace the burst section. With the five in you are pretty much out of luck, unless of course you have another supply line, or have enough tank water to funtion untill the line is operational again.

My FD went to 4" supply line in 2002 after years of dropping dual 3's.
Better water flow, less line to pick up and you don't have to wash and hang it!

Cap,

If I am figuring correct, dual 3's, if pumped at 285 will outperform a single 4" pumped at 185 if you are using single jacket supply grade 4".

For 500 GPM, Pumped at 285 for 3" and 185 for the 4"...
approx 5300 feet for the dual 3's
approx 3300 feet for the single 4" if its supply grade hose. If its attack grade (300 PSI rating) then its equivalent to the dual 3's.

1000 gpm at 285 psi? Real decent hydrant pressure, large pumps, and short lays? It certainly seems that while it works in many places, switching to it from 5" would make little sense. How manueverable does the supply line need to be?

If I am figuring correct, dual 3's, if pumped at 285 will outperform a single 4" pumped at 185 if you are using single jacket supply grade 4".

For 500 GPM, Pumped at 285 for 3" and 185 for the 4"...
approx 5300 feet for the dual 3's
approx 3300 feet for the single 4" if its supply grade hose. If its attack grade (300 PSI rating) then its equivalent to the dual 3's.

The question is.. why?

Pumping at dual 3's 285 PSI puts a lot of uncessary strain, wear and tear on the engine and transmission of the pumper, using more fuel.

The noise factor at the pump panel is enough to deafen the pump operator, who, if he not wearing a headset or has the portable glued to his ear may miss an important radio transmission that could have life or death circumstances.

‎"The education of a firefighter and the continued education of a firefighter is what makes "real" firefighters. Continuous skill development is the core of progressive firefighting. We learn by doing and doing it again and again, both on the training ground and the fireground."
Lt. Ray McCormack, FDNY

The point made by most here is very valid. Bigger is more efficient, theres no argument. I hope you guys understand I am just providing some analysis, not saying switching to 3's is a good idea, but simply showing what it can do. If someone wants to make a change, shouldnt we provide some good workable arguments and data, not just the typical "thats stupid"?

Cap, I would say that the engine would be quite content purring away at the RPM's required to produce 285, its probably less strain than truckin down the highway pedal to the metal goverened out at 2100RPM! But youd need to ask some of the motorheads in the apparatus forum to get a mechanics perspective.

Anyway, point is, the most efficient way to move mas agua is with the bigger hose at lower RPM's through the shortest lay possible. That cant be argued.

1) You already have 5 inch hose. When you have a fire there is one hose to lay, one hose to pick up and under almost 100% of your fires it will give you all the water you need with just hydrant pressure alone, well within reasonable hose lays lengths. Plus hose off the chunks and reload it.

2) You talk of switching to or adding a 3 inch hose option. Why? The downsides are clear. First the need to purchase new hose and defend the purchase. How would you defend it? Golly City Administrator we want to buy twice as much 3 inch hose with a less capability because we are too lazy to pick up 5 inch hose when we need water from a hydrant. Secondly, unless you are going to pump those lines or keep your lays under a couple hundred feet you will never maximize the capability of that hydrant. This forces someone else to supply you at a larger incident. Not very efficient.

I just don't see any logical reason for making this switch backwards. Good luck on justifying it because it is going to be a completely uphill battle in snow to your ***.

Caught a job in a duplex just last night. Layed one 3" line for supply and a 1 3/4 attack and one more for backup. Fire in kitchen on both sides with fire in the walls extending to the common attic. Fire out in 10 mins. damage contained to kitchens, ceiling, dividing kitchen walls, and the big hole I put on the roof. Smoke damage of course.......One 3" supply.....Nothing more needed. Both families will probably go back in a couple of weeks depending on how fast they get the repairs done.

Caught a job in a duplex just last night. Layed one 3" line for supply and a 1 3/4 attack and one more for backup. Fire in kitchen on both sides with fire in the walls extending to the common attic. Fire out in 10 mins. damage contained to kitchens, ceiling, dividing kitchen walls, and the big hole I put on the roof. Smoke damage of course.......One 3" supply.....Nothing more needed. Both families will probably go back in a couple of weeks depending on how fast they get the repairs done.

Good for you. And if the house would have taken off your single 3 inch line would have proved inadequate requiring either a hand stretch of a second line to the hydrant OR another comapny to supply you, or even better a second company to lay in their own lines and attack the fire.

Frankly, this type of operation speaks to me as nothing more than laziness and inefficiency. It becomes even more bizarre if the engine decides to lay dual 3 inch lines because there is twice as much hose to pick up. The original poster has 5 inch hose already and wants to switch to using 3 inch in either single or dual line lays. Sorry but this is just stupid and I can;t say it any other way for it to have the power I want it to.

If it works for you and you have been lucky enough to not get caught by your unwillingness to reload ldh, good for you. But I would bet more than a few times it has not been enough and the scenarios I described above have come to fruition.

Good for you. And if the house would have taken off your single 3 inch line would have proved inadequate requiring either a hand stretch of a second line to the hydrant OR another comapny to supply you, or even better a second company to lay in their own lines and attack the fire.

Frankly, this type of operation speaks to me as nothing more than laziness and inefficiency. It becomes even more bizarre if the engine decides to lay dual 3 inch lines because there is twice as much hose to pick up. The original poster has 5 inch hose already and wants to switch to using 3 inch in either single or dual line lays. Sorry but this is just stupid and I can;t say it any other way for it to have the power I want it to.

If it works for you and you have been lucky enough to not get caught by your unwillingness to reload ldh, good for you. But I would bet more than a few times it has not been enough and the scenarios I described above have come to fruition.

FyredUp

If its blowing through the roof, then we will drop the 5". if we think we need more than one 3, then yes a second rig will lay in. We get our fires out and to date I can not think of a time where we got in a bind. It does work for us. at my old job, all we had was 5" and I guess I am lazy,because picking up 600' of 5" for a room and contents that was put out with the booster tank is a lot more work than dropping the 3".

If its blowing through the roof, then we will drop the 5". if we think we need more than one 3, then yes a second rig will lay in. We get our fires out and to date I can not think of a time where we got in a bind. It does work for us. at my old job, all we had was 5" and I guess I am lazy,because picking up 600' of 5" for a room and contents that was put out with the booster tank is a lot more work than dropping the 3".

You see admitting the problem is the first step on the road to recovery.

With my volly FD the hope that someone will arrive with the second engine OR mutual aid will arrive in a timel manner has made us become self sufficient and if having to pick up dry 5 inch on occasion is the cost of being ready if it gets ****ty so be it.

With my career FD with the second engine close behind the first engine may go straight in and attack off from tank water and the second in lays in to supply them, with a 5 inch line. Small FD and we can;t afford to make a mistake in the water supply area because manpower to fix it is a premium.

Although I have a point about picking up hose. Yesterday the engine laid 300feet of 5 inch for a standby at a major supply line gas leak. When we picked up both engine crews and the ladder crew helped pick it up and reload it. We were done in about 7 or 8 minutes. Maybe you guys don't help each other pick up where you are...

‎"The education of a firefighter and the continued education of a firefighter is what makes "real" firefighters. Continuous skill development is the core of progressive firefighting. We learn by doing and doing it again and again, both on the training ground and the fireground."
Lt. Ray McCormack, FDNY

The only supply line that we run with is 3 inch. Every fire we run, the supply engine drops two supply lines, both of which are 3 inch. We donít charge both unless needed, but we drop two every time.
Our three inch also is used for our exposure/outside operation lines as well.
Each of our engineís carry twin boxes of 15 sections of 3 inch, and operate out of a reverse lay operation.

Iíve never worked with 5 inch, so I donít know anything about the stuff. I will say that it does suck picking up 3 inch when the supply engine has a two block stretch for a hydrant, though.

The only supply line that we run with is 3 inch. Every fire we run, the supply engine drops two supply lines, both of which are 3 inch. We donít charge both unless needed, but we drop two every time.
Our three inch also is used for our exposure/outside operation lines as well.
Each of our engineís carry twin boxes of 15 sections of 3 inch, and operate out of a reverse lay operation.

Iíve never worked with 5 inch, so I donít know anything about the stuff. I will say that it does suck picking up 3 inch when the supply engine has a two block stretch for a hydrant, though.

Yup.. been there, done that.

Ever notice that the "dual charged 3 inch two block long stretches" only occur when it is cold enough to freeze the balls off a brass monkey?

‎"The education of a firefighter and the continued education of a firefighter is what makes "real" firefighters. Continuous skill development is the core of progressive firefighting. We learn by doing and doing it again and again, both on the training ground and the fireground."
Lt. Ray McCormack, FDNY

I am on a department where the only supply hose we lay is 5", on everything. We have plenty of hydrants and the water system comes from the "big city" right next to us so amount and pressure is not really an issue. Some of us are talking about the idea of going to 3" or dual 3's for residentual fire runs. Some of the reasoning behind this is the gpm's you can get from 3" would be significant to supply attack lines on residentual fires and maneuverability of the hose on the ground. I would like to hear from everyone especially from those that lay 3" or dual 3's. What is your reasoning for it and what are the pro's and con's.

Whats your manpower situation? Are you planning on keeping the 5" as well? I would keep the 5". How long are you drives and stuff to lay in? Do you lay in and commit 1 truck to the fire and have another hit the supply line out at the street or do you bring up more then one truck up the drive? We have ran LDH hose for several years now and have no problems. Even loading it is simple. I hope your dept makes a good decission on this.